1. Field of the Invention
The present invention relates to a slot machine that executes a free game and a slot machine that increases the number of displayed special symbols.
2. Discussion of the Background
There have conventionally been known slot machines that scroll-display and then stop-display a plurality of kinds of symbols and provide a predetermined amount of game media (e.g. a predetermined number of coins, a predetermined amount of money) based upon a combination of the stop-displayed symbols. Such slot machines are disclosed in, for example, U.S. Pat. No. 6,960,133, U.S. Pat. No. 6,012,983, and U.S. Pat. No. 6,093,102.
Among such slot machines, there exists a slot machine executing a free game in a case where a predetermined condition (e.g. rearrangement of the specific symbol in a slot machine game) is established in a game. The free game is a game conducted without a BET of game media. For example, AU-1972901-A discloses a slot machine which executes a free game as a side game when a predetermined condition (specific rearrangement of symbols) has been established.
Since a player can play a game without consuming game media in the free game, the player is generally playing a game with strong expectations for generation of the free game. Further, a content of the free game, a condition for generation of the free game and the number of the free games are of great concerns for the player.
Accordingly, the inventors of the present invention have come to consider that adding a new feature concerning the content of the free game, the condition for generation of the free game and the number of the free games can enhance the player's interest and concern for the game.
The present invention was made in view of the aforementioned issue and an object thereof is to provide a slot machine capable of enhancing the player's interest and concern for the game, and a control method thereof.
There have conventionally been known slot machines that scroll-display and then stop-display a plurality of kinds of symbols and provide a predetermined amount of game media (e.g. a predetermined number of coins, a predetermined amount of money) based upon a combination of the stop-displayed symbols.
Among such slot machines, there exist slot machines having special symbols different from normal symbols. As one of the special symbols, a wild symbol is known which can be substituted for another symbol. Slot machines having the wild symbols are disclosed for example in US 2006/0084498-A1, US 2006/0264254-A1, and US 2008/0070673-A1. In the slot machine having the wild symbol, when the wild symbol is displayed on a pay line, the wild symbol is substituted for another symbol to form a combination establishing a prize, thus allowing a player to have great expectations.
Therefore, the inventors of the present invention have come to consider that adding a new function concerning the wild symbol to the slot machine can provide a more attractive game.
The present invention was made in view of the aforementioned issue and an object thereof is to provide a slot machine capable of providing a more attractive game, and a control method thereof.
The contents of U.S. Pat. No. 6,960,133, U.S. Pat. No. 6,012,983, U.S. Pat. No. 6,093,102, US 2006/0084498-A1, US 2006/0264254-A1, and US 2008/0070673-A1 are incorporated herein by reference in their entirety.